Segmented sliding yardsticks error tolerant fingerprint enrollment and verification system and method
First Claim
1. A biometric enrollment and verification method comprising the steps of:
- obtaining biometric image signals for an image to be verified;
obtaining a data structure for an enrolled image, said data structure having a plurality of yardsticks in a predetermined order, each said yardstick comprising a one dimensional pixel array having a predetermined number of either horizontal or vertically oriented, consecutive, co-linear pixels corresponding to a predetermined portion of a row or column of pixels within said enrollment image, each yardstick having a predetermined spatial relationship within said enrollment image relative to each of said other yardsticks, the maximum number of said yardsticks being substantially smaller than the maximum number extractable from the enrollment image and organized into a plurality of adjacent segments, comparing said yardsticks to an image to be verified by comparing segments of each yardstick to corresponding linear patterns in the image to be verified, wherein the result of the comparison of segments in a particular yardstick determines if said yardstick has found a match.
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Abstract
A fast position tolerant and economical fingerprint verification algorithm and software implementation is disclosed. The algorithm has very important advantages in comparison to existing fingerprint verification algorithms like minutia extraction or full image analysis based on a series of two dimensional fast Fourier transforms ( FFT'"'"'s) and two dimensional cross correlation in speed, compactness of the template and finger positioning for verification. It is based on a small “yardstick” pattern being moved inside the image to be verified, and when a match is found the rest of the verification process is started. The yardstick is divided into segments in order to fit different DSP and microcontroller register lengths and structures. The software code implements the algorithm in the most efficient way for utilization on a digital signal processor architecture. A main area of application is in fingerprint identification and verification, but it could be implemented with same success in other image verification systems like iris, eye, face etc., where two images should be compared. The algorithm is adaptive, so various false acceptance and false rejection coefficients could be utilized very easily. It also produces a very compact template, which leads to better memory utilization in fingerprint databases.
69 Citations
54 Claims
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1. A biometric enrollment and verification method comprising the steps of:
- obtaining biometric image signals for an image to be verified;
obtaining a data structure for an enrolled image, said data structure having a plurality of yardsticks in a predetermined order, each said yardstick comprising a one dimensional pixel array having a predetermined number of either horizontal or vertically oriented, consecutive, co-linear pixels corresponding to a predetermined portion of a row or column of pixels within said enrollment image, each yardstick having a predetermined spatial relationship within said enrollment image relative to each of said other yardsticks, the maximum number of said yardsticks being substantially smaller than the maximum number extractable from the enrollment image and organized into a plurality of adjacent segments, comparing said yardsticks to an image to be verified by comparing segments of each yardstick to corresponding linear patterns in the image to be verified, wherein the result of the comparison of segments in a particular yardstick determines if said yardstick has found a match. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 39)
- obtaining biometric image signals for an image to be verified;
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37. An enrollment system for biometric identification device, having
an input device to provide signals representing an enrollment image, a memory, and a control system coupled to said memory, wherein said control system includes a processing unit to extract yardsticks from said enrollment image, each said yardstick comprising a one dimensional pixel array having a predetermined number of either horizontal or vertically oriented, consecutive, co-linear pixels corresponding to a predetermined portion of a row or column of pixels within said enrollment image, each yardstick having a predetermined spatial relationship within said enrollment image relative to each of said other yardsticks, the maximum number of said yardsticks being substantially smaller than the maximum number extractable from the enrollment image and each yardstick being divided into a predetermined number of adjacent, multiple pixel segments, and wherein said control system causes said yardsticks to be stored in said memory.
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40. A biometric enrollment and verification system, comprising:
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an input device to acquire biometric images, a memory to store the acquired images from said input device, a central processor unit to control and synchronize the operation of said biometric enrollment and verification system, and a data structure including a plurality of yardsticks in a predetermined order, each said yardstick comprising a one dimensional pixel array having a predetermined number of either horizontal or vertically oriented, consecutive, co-linear pixels corresponding to a predetermined portion of a row or column of pixels within said enrollment image, each yardstick having a predetermined spatial relationship within said enrollment image relative to each of said other yardsticks, the maximum number of said yardsticks being substantially smaller than the maximum number extractable from the enrollment image and organized into a plurality of adjacent segments, wherein said central processor unit compares said yardsticks for a match to a biometric image to be verified by comparing sequentially segments of each yardstick to corresponding linear patterns in the image to be verified, wherein the result of the comparison of all segments in a particular yardstick determines if said yardstick has found a match. - View Dependent Claims (41)
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42. In a biometric enrollment and verification system stored on a computer-readable medium, comprising the steps of:
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acquiring data representing an image to be verified;
obtaining a plurality of sets of data each representing a set of co-linear pixels from an enrolled image said set being called yardstick and each said yardstick comprising a one dimensional pixel array having a predetermined number of either horizontal or vertically oriented, consecutive, co-linear pixels corresponding to a predetermined portion-of a row or column of pixels within said enrollment image, each yardstick having a predetermined spatial relationship within said enrollment image relative to each of said other yardsticks, the maximum number of said yardsticks being substantially smaller than the maximum number extractable from the enrollment image, each set of data including a plurality of subsets, each subset representing a segment of said yardstick;
accessing said subsets of data; and
comparing said subsets with data for said image to be verified, outputting a verification result after comparing. - View Dependent Claims (43, 44)
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45. A biometric image enrollment method comprising the steps of:
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providing an enrollment image representation and obtaining digitized enrollment image data;
obtaining a plurality of sets of pixel data from said enrollment representation called yardsticks, each said yardstick comprising a one dimensional pixel array having a predetermined number of either horizontal or vertically oriented, consecutive, co-linear pixels corresponding to a predetermined portion of a row or column of pixels within said enrollment image, each yardstick having a predetermined spatial relationship within said enrollment image relative to each of said other yardsticks, the maximum number of said yardsticks being substantially smaller than the maximum number extractable from the enrollment image, dividing said sets of pixel data into a plurality of subsets corresponding to adjacent segments of said co-linear pixels; and
storing said subsets of pixel data in a memory. - View Dependent Claims (46)
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47. A method of biometric enrollment and verification comprising the steps of:
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acquiring data representing an image to be verified;
obtaining a plurality of sets of data each representing a set of co-linear pixels from an enrolled image said set being called yardstick and each said yardstick comprising a one dimensional pixel array having a predetermined number of either horizontal or vertically oriented, consecutive, co-linear pixels corresponding to a predetermined portion of a row or column of pixels within said enrollment image, each yardstick having a predetermined spatial relationship within said enrollment image relative to each of said other yardsticks, the maximum number of said yardsticks being substantially smaller than the maximum number extractable from the enrollment image, each set of data including a plurality of subsets, each subset representing a segment of said yardstick;
accessing said subsets of data; and
comparing said subsets with data for said image to be verified, outputting a verification result after comparing. - View Dependent Claims (48, 49, 50, 51, 52, 53, 54)
wherein after a first sufficient match has been found for a said yardstick;
a plurality of further matches is sought in said comparing step;
wherein each said further match is sought at only limited numbers of respective locations relative to a location where a prior match had been determined.
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50. The method of claim 47 wherein said step of obtaining a plurality of sets of data includes accessing a stored data structure which contains said sets of data in a predetermined order.
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51. The method of claim 47 wherein said comparing step, after finding a first match for a said yardstick, compares at least one other one said yardsticks to limited numbers of locations within the data for the image to be verified.
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52. A biometric image verification method according to claim 47 wherein said comparing step verifies the acquired data as corresponding to an enrolled image, even if a limited number of said subsets of said enrolled sets of data are not found to be sufficiently matched to said acquired data.
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53. The method of claim 47 wherein said accessing and comparing steps comprise:
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accessing a first one of said sets of data;
accessing a first subset from said first set;
then comparing said first subset with said data for said image to be verified in a plurality of locations until a match has been found;
then sequentially comparing one or more further subsets from said first set and comparing each said further subset to said data for said image to be verified at locations corresponding to the position of the pixels represented by said further subset relative to the positions of the pixels represented by said first subset, until a sufficient number of subsets have been matched to data for said image to be verified;
then accessing one or more further sets of data and comparing the subsets of each at only limited numbers of locations relative to the location at which a match was found for a previously matched set of data; and
determining whether the image to be verified corresponds to the enrolled image as a function of the matches located in said sets and subsets of data.
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54. The method of claim 53 wherein a set of data is determined to have been matched after a predetermined number of subsets thereof have been found to match the data for said image to be verified.
Specification